The Population Center has the following primary cores: PRIMATE FACILITIES, TISSUE CULTURE SERVICE, MASS SPECTROMETRY, STATISTICAL SERVICES AND SEXUAL BEHAVIOR. Experimental studies are concerned with the primate neuroendocrine control of reproduction, cytogenetic investigation of human ovarian and testes lines, the biochemistry of steroid and polypeptide hormones, the investigation of ovarian and adreno-cortical steroid pathways with mass spectrography, the biosocial problems of populations, and the psychosexual and endocrine evaluation of human sexual behavior.